5,058 research outputs found
Secondary-electron radiation accompanying hadronic GeV-TeV gamma-rays from supernova remnants
The synchrotron radiation from secondary electrons and positrons (SEPs)
generated by hadronic interactions in the shock of supernova remnant (SNR)
could be a distinct evidence of cosmic ray (CR) production in SNR shocks. Here
we provide a method where the observed gamma-ray flux from SNRs, created by
pion decays, is directly used to derive the SEP distribution and hence the
synchrotron spectrum. We apply the method to three gamma-ray bright SNRs. In
the young SNR RX J1713.7-3946, if the observed GeV-TeV gamma-rays are of
hadronic origin and the magnetic field in the SNR shock is mG,
the SEPs may produce a spectral bump at eV, exceeding the
predicted synchrotron component of the leptonic model, and a soft spectral tail
at keV, distinct from the hard spectral slope in the leptonic
model. In the middle-aged SNRs IC443 and W44, if the observed gamma-rays are of
hadronic origin, the SEP synchrotron radiation with G can
well account for the observed radio flux and spectral slopes, supporting the
hadronic origin of gamma-rays. Future microwave to far-infrared and hard X-ray
(>100keV) observations are encouraged to constraining the SEP radiation and the
gamma-ray origin in SNRs.Comment: 9 pages, 5 figures and 1 table, MNRAS accepte
New predictions on the mass of the light hybrid meson from QCD sum rules
We calculate the coefficients of the dimension-8 quark and gluon condensates
in the current-current correlator of light hybrid current
. With inclusion of these
higher-power corrections and updating the input parameters, we re-analyze the
mass of the light hybrid meson from Monte-Carlo based QCD sum rules.
Considering the possible violation of factorization of higher dimensional
condensates and variation of , we obtain a conservative
mass range 1.72--2.60\,GeV, which favors as a better hybrid
candidate compared with and .Comment: 12pages, 2 figures, the version appearing in JHE
Numerical study of synchrotron and inverse-Compton radiation from gamma-ray burst afterglows with decaying microturbulence
The multiwavelength observations of GRB afterglows, together with some
high-performance particle-in-cell simulations, hint that the magnetic field may
decay behind the shock front. In this work, we develop a numerical code to
calculate the evolution of the accelerated electron distribution, their
synchrotron and inverse-Compton (IC) spectra and accordingly the light curves
(LCs) under the assumption of decaying microturbulence (DM) downstream of the
shock, with the fluid proper
time since injection. We find: (1) The synchrotron spectrum in the DM model is
similar to that in the homogeneous turbulence (HT) model with very low magnetic
field strength. However, the difference in the IC spectral component is
relatively more obvious between them, due to the significant change of the
postshock electron energy distribution with DM. (2) If the magnetic field decay
faster, there are less electrons cool fast, and the IC spectral component
becomes weaker. (3) The LCs in the DM model decay steeper than in the HT model,
and the spectral evolution and the LCs in the DM model is similar to the HT
model where the magnetic field energy fraction decreases with observer time,
. (4) The DM model can naturally
produce a significant IC spectral component in TeV energy range, but due to the
Klein-Nishina suppression the IC power cannot be far larger than the
synchrotron power. We apply the DM model to describe the afterglow data of GRB
190114C and find the magnetic field decay exponent and the
electron spectral index . Future TeV observations of the IC emission
from GRB afterglows will further help to probe the poorly known microphysics of
relativistic shocks.Comment: 14 pages, 9 figures, 3 tables, submitted to MNRAS, comments welcom
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